Video film projector

ABSTRACT

A film-coding and code-reading device for a motion picture projector comprises a film-edge-notching punch and a film edge notch sensor. The punch and sensor are disposed in coaxial relationship within the projector gate whereby any desired film frame may be editorily marked.

States atom Chamberlain Feb. 15, 1972 [54] VIDEO FILM PROJECTOR2,177,788 10/1939 Ross ..352/130X 3,139,793 7/1964 Bradford et al.....352/92 X [72] Inventor. Earl Chamberlain, PO. Box 603, Mount3,432,228 3/1969 Helmund 352/92 UX Hemmm Cahf- 9541 3,515,470 6/1970Browder ..352/92 [22] Filed: Nov. 12, 1969 Primary ExaminerLouis R.Prince PP ,896 Assistant Examiner-Joseph W. Roskos p Attorney-Fryer,Tjensvold, Feix, Phillips & Lempio [52] U.S.Cl ..352/92,352/l30, 352/236[51] lnLCl. ..G03b 21/50 [57] ABSTRACT [58] Field of Search .352/92,130,236 A film-coding and code-reading device for a motion p r projectorcomprises a film-edge-notching punch and a film [56] References Citededge notch sensor. The punch and sensor are disposed in coaxialrelationship within the projector gate whereby any UNITED STATES PATENTSdesired film frame may be editorily marked. 2,151,822 3/1939 Winchester352/130 2 Claims, 11 Drawing Figures PATENTEDFEB 15 I972 SHEET 1 [IF 3,INVENTOR EARL CHAMBERLIN FIG. 2

ATNEY 7 PATENTEUFEB 15 I972 3.642.355

SHEET 2 0F 3 FIG. 3

INVENTOR EARL CHAMBERLIN PATENTEDFEB 15 I972 SHEET 3 BF 3 1 l G I FFIG.1O

INVENTOR \RL CHAMBERLIN A'FTONEY;

VIDEO FILM PROJECTOR This invention is related to the field of motionpicture projectors. Typically, motion picture projectors display aseries of pictures developed from a series of exposures made by a motionpicture camera. The exposures are made and developed on a long strip offilm. The projector displays the pictures by directing a beam of lightthrough the transparent picture disposed in the projector aperture. Anappropriate lens is em ployed to focus the image of the picture on aremote screen. The light from the aperture is then blanked by some kindof a shutter while the film strip is indexed to the next picture on thefilm, whereupon the light through the aperture is unblanked and the nextpicture in the series is displayed on the screen. In this way theprojector displays a series of pictures on the screen. 1

The effect of motion pictures is achieved by displaying a series ofstill pictures to the eye because the retina retains .an image for ashort time after the image is no longer being viewed by the eye. Thisretention of an image by the retina after it is no longer being viewedby the eye is known as visual persistance." lf the eye is shown anotherpicture while the first picture is still retained on the retina, and thesecond picture is not very different from the first, the change will beseen, but will not be recognized. Thus, a rapid series of slightlydifferent pictures will be interpreted by the mind as motion.

if the pictures, or frames, are displayed at the same speed at whichthey were taken by the camera, the resulting apparent motion will beseen at the same speed at which it occurred, regardless of what theframe speed might be. However, if the sequential pictures are to be onlyslightly different, the frame speed must be increased as the speed ofthe motion photographed increases.

In photographing and displaying any given action or motion, it isdesired to minimize the number of frames required, and thus minimize theamount of film required. Less film means reduced film storagerequirements in the camera and the projector. and reduced film and filmdevelopment costs.

However, as the number of frames used to record a motion is decreased,the frame speed is likewise necessarily decreased. Thus motion picturesystems must compromise between a desire to minimize the amount of filmrequired to record a motion and the desire to prevent the observance offlicker and jerk" by the viewers of the program shown.

Flicker" is the detection by the eye of the blanking of the light fromthe projector while the frames are changed. Jerk is the detection by theeye of a series of discrete pictures.

Flicker can be reduced by shortening the amount of time that theprojector is blanked and the screen is dark.

Jerk can be reduced by increasing the rate at which the pictures areshown to the eye. Alternatively, it can be reduced by slowing down theresponse of the eye until it is no longer able to detect a series ofdiscrete pictures.

It has been found that, within limits, visual persistance, or theresponse of the eye to different images, is greatly affected by thebrightness of the images viewed. Thus, if a picture projected on ascreen is not interrupted by a shutter until it is changed, more lightwill enter the eye while the picture is projected, and visualpersistance will be enhanced.

Accordingly, it is an object of this invention to change frames in amotion picture projector at a very high speed which is independent ofthe frame speed of the projector.

it is another object of this invention to operate the shutter of amotion picture projector at a very high speed to blank the aperture onlywhile the frames are being changed.

It is another object of this invention to operate a motion pictureprojector at a variable frame speed in accordance with the speed ofmotion being reproduced.

It is a further object of this invention to utilize the reduced filmstorage requirements of the projector employing a film storage cassettewhich is easily insertable into the projector, and requires nosubsequent threading operations.

Another object of this invention is to be able to encode any particularframe of the film while it is in the aperture of the projector which canlater be detected when the frame is again in the projector aperture toinitiate any desired operation, such as a timed pause in the filmadvance.

It is another object of this invention to automatically take up the filmas it emerges from the gate of the projector and store it temporarily ona takeup reel located within the projector.

it is another object of this invention to automatically rewind the filmfrom the takeup reel onto the cassette reel upon reaching the end of thefilm.

As was mentioned, in order to authentically reproduce a given motion,the film frames must be projected at the same speed that they werephotographed.

The most common way of doing this is to standardize upon certain framespeeds throughout the industry. The great disadvantage in such constantspeed systems was that the standard frame speeds had to be fast enoughto reproduce the fastest anticipated motion without a jerky appearance.The average motion in a motion picture is considerably slower than thefastest motion, and the result was that great quantities of film werewasted because the system was running faster than necessary most of thetime.

To minimize film footage, a variable speed system is required. In such asystem, the expert cameraman operates his camera at the minimum speed towhich he knows from experience is fast enough to record the motion beingphotographed without jerk. Such variable speed cameras record theirspeed of operation on a program which is later used to control thespeedof the projector when projecting the film. The best way of producingsuch a frame speed program is by use of an electronic circuit whichincludes a switch operated by the film frame change mechanism of thecamera to produce electrical impulses upon the change of film frames inthe camera, which are recorded on a magnetic tape.

in the past, the speed of the projector has been compared with the speedof the camera as recorded in the frame speed program, and adjustedaccordingly. This was done by means of electronic and mechanical devicesused in conjunction with the projector.

My invention represents a great improvement over the prior art. Myprojector is operated directly by the electrical impulses recorded onthe frame speed program tape. The tape may be played" on any taperecorder at the speed at which it was recorded, and the output of therecorder fed directly to the projector. For sound capabilities, thespeed program may be recorded on another track" of the same tape and thetwo may be played simultaneously on one tape recorder when using myprojector.

My projector utilizes a linear motor to respond directly to theelectrical impulses recorded on the frame speed tape to operate a framechange mechanism having a fast operating time.

ln addition, I have employed a butterfly shutter which is engageddirectly by the film and is held shut while the film is moving throughthe aperture. The shutter comprises a very light rotating vane thatflips closed and open at a very fast speed.

My projector also includes a cassette which extends into the projectorto form a portion of the projector gate. The film is wound on a reeldisposed within the cassette. The end of the film is held lightlybetween two surfaces which form an opening in the cassette and comprisea portion of the projector gate when the cassette is inserted in theprojector. Thus, upon insertion of the cassette into the projector, thefilm is already in the gate and ready to be advanced by the film advancemechanism The projector also includes a punch for placing a notch in theedge of the film at any desired location. Such notches are in common usein the industry for a number of purposes. However, with prior artdevices for notching the film, it has been impossible to achieve anydegree of accuracy in locating the notch on the film with respect to thedesired frame. My invention makes it possible to choose the exact frameat which the notch will be detected by the projector. This isaccomplished by locating the notch puncher andthe notch detector at thesame location on the path of the film. The punch comprises a hollowcylinder having one side which is partially cut away and which partiallyoverlaps the film. The notch detector is disposed within the punch andrides lightlyon the edge of the film. When a notch registers with thepunch, the detector emerges from the cutaway side of the punch to followthe edge of the film. The movement of the detector closes a microswitchwhich activates the desired circuit.

My projector also employs an improved gate which minimizes the effectsof distortion of the film from thermal expansion. When the film isdisposed within the aperture of a projector it is usually subjected torather high temperatures resulting from the energy radiated by the lightsource, most of which is directed through the film. The resultingthermal expansion of the film causes distortion which affects the focusof the projected image. In the past, automatic focusing devices havebeen employed to maintain a sharp image on the screen. I have found thatthis distortion of the film can be minimized by employing a gate havinga slight longitudinal curve, which causes the film to be slightly flexedlongitudinally.

Further objects and advantages of the present invention and the mannerin which it is carried into practice will be apparent from the followingdescription and claims and are illustrated in the accompanying drawingswhich, by way of illustration, show preferred embodiments of the presentinvention and the principles thereof and what are now considered to bethe best modes contemplated for applying these principles. Otherembodiments of the invention embodying the same or equivalent principlesmay be used and structural changes may be made as desired by thoseskilled in the art without departing from the present invention withinthe purview of the appended claims.

In the drawings:

FIG. 1 is a perspective view of my projector with part of the case cutaway;

FIG. 2 is a side elevation view of my projector with the gate shown insection;

FIG. 3 is an exploded perspective view of the opposite side of theprojector from that shown in FIG. 1, showing the film cassette and reel;

FIG. 4 is a partial enlarged sectional elevation view of the area of theprojector indicated by the arrows C in FIG. 3, with the cassetteinserted in the projector.

FIG. 5 is an enlarged perspective view of the shutter of my projector,indicated by the arrows A in FIG. 1;

FIG. 6 is a side elevational view in section of the shutter shown inFIG. 5, showing the shutter in the closed position;

FIG. 7 is a side elevational view in section of the shutter shown on theopen position;

FIG. 8 is a top plan view of shutter taken along the line and in thedirection indicated by the arrows 88 in FIG. 7;

FIG. 9 is a sectional view of the takeup reel and rewind wheel assemblytaken along the line and in the direction indicated by the arrows 9-9 inFIG. 2.

FIG. 10 is an enlarged perspective view of my film coder shown in thearea indicated by the arrows B in FIG. 1; and

FIG. 11 is an end view ofthe coder shown in FIG. 10.

In FIG. 1 a projector is shown having a gate 15 formed by members 16 and17 and cassette 18. Members 16 and 17 are slightly curved longitudinallyto prevent distortion of the film from thermal expansion, and include anaperture 19. In operation, film feeds out of cassette 18 at its mouth 20and down through gate 15, past aperture 19, along guide 21 and on totakeup reel 22 as hereinafter described.

As shown in FIG. 3, film 23 is stored on a reel 24 disposed withincassette 18 which is formed of some suitable material such as plastic.Cassette 18 has a mouth shown generally at 20 which, as shown in FIG. 4,comprises a lower lip 25 and an upper lip 26, which overlaps lower lip25.

When cassette 18 is inserted in the projector, mouth 20 is aligned withmembers 16 and 17 and forms a portion of gate 15. The end of film 23extends between lips 25 and 26 to the lower edge of lip 25, whichincludes a slot 27. As shown in FIGS. 4 and 2, claw 28 is positionedadjacent to the depending end of film 23 and is operable to engage thefilm and advance it through the gate in the manner described below.

Referring to FIG. 1, a linear motor 30 includes a rod 31 which ispivotally connected to one end of a lever 32 which is pivotallyconnected to frame 14 at a point intermediate its ends. The other end oflever 32 is pivotally connected to a link 33 which in turn is pivotallyconnected to claw 28. One end of claw 28 includes a slot 34 which slideson pin 35 attached to frame 14.

When a signal is received by linear motor 30, it is energized, and rod31 extends rotating lever 32 counterclockwise as viewed in FIG. 1. Thelower end of lever 32 exerts a force, through link 33, on claw 28 whichis allowed to slide towards the film by slot 34. Points 29 on claw 28engage the film, slightly penetrating lower lip 25 through slot 27. Atthis time pin 35 reaches the outer end of slot 34, whereupon claw 28stops moving toward the film and begins to rotate downward around pin 35as lever 32 continues to turn. As claw 28 rotates downward, teeth 29penetrate perforations 36 in the film and move the film down through thegate until lever 32 and 33 are fully extended, at which time linearmotor 30 is deenergized, and the claw is withdrawn from the film andreturned to its original position against stop 38 by spring 39.Successive im pulses fed to linear motor 30 will cause the claw tosuccessively advance the film one frame at a time through the gate as itengages :successive perforations in the film and pulls it downward adistance equal to the height of a frame.

Referring to FIG. 2, it will be seen that as the film moves through thegate it will move past aperture 19 within which is disposed a shuttershown generally at 40.

Referring to FIG. 5, shutter 40 is shown as comprising a cylinder 41having its ends journaled into member 17 on either side of the aperture.Near one end of the cylinder, a flat tab 42 projects radially from thecylinder and is of appropriate size and position to engage perforations36 in film 23, shown in phantom. Projecting from cylinder 41diametrically opposite tab 42 is a vane 43, of sufficient size toobstruct the aperture.

As shown in FIG. 6, when film 23 moves downward, perforation 36 is movedout of registration with tab 42. As a result, tab 42 is pushed downwardand held down by the film until the next perforation registers with thetab whereupon cylinder 41 returns to its original position, shown inFIG. 7, under the force of torsional spring 44.

As shown in FIG. 6, when cylinder 41 is rotated by the downwarddeflection of tab 42, vane 43 is'deflected upward and obscures aperture19 while the film is being indexed to the next frame, whereup it returnsto its original position shown in FIG. 7, once again opening theaperture.

It will be appreciated that the speed at which the claw advances thefilm, and consequently closes the shutter, can be quite fast dependingonly upon the design of the components, without regard to the framespeed being used.

Referring again to FIG. 2, as the film moves farther through the gate,it moves past a coder shown generally 45. As shown in FIG. 10, coder 45comprises a hollow cylindrical punch 46, having one side partially cutout, and which cooperates with a die 47 to cut an arcuate notch in theedge of film 23 when the punch is manually operated by means of tab 48,extending from one side of the punch through the projector frame. An arm49, pivoted at engages the edge of the film at the center of the punchso that when an arcuate notch registers with the punch, the arm willpivot under the force of spring 50, closing a microswitch 71 whichactuates any desired circuit such as the delay circuit disclosed in mycopending application Ser. No. 765-081.

Referring again to FIG. 2, as the film moves out of the gate it isguided onto takeup reel 52. As shown in FIG. 9, one flange of reel 52includes an annular ring 53. A rewind wheel 54 is mounted concentricallywithin ring 53 on shaft 55 which extends coaxially through projectorframe 14 and reel axle 56, and is connected to spindle 57 upon which ismounted cassette reel 24.

A motor 58 drives pulley 59 carried by arm 61 which is pivotally mountedon the projector frame. Pulley 59 includes a shaft 60 which projectsinto the annular space between ring 53 and wheel 54. A lever 62 has oneend rigidly connected to arm 61, and its other end pivotally connectedto rod 63 of solenoid 64.

In operation, tension spring 65 attached to rod 63 exerts a force on rod63, which in turn exerts a torque on arm 61 by means of lever 62,causing shaft 60 of pulley 59 to bear against annular ring 53. Thus, asmotor 58 drives pulley 59 and shaft 60, the shaft exerts a frictionalforce on the annular ring of the takeup reel, causing the takeup reel torotate and take up the film until the film between the reel and the gatebecomes taut, at which time shaft 60 will slip with respect to ring 53.

As shown in FIG. 3, a spring wire finger 67 projects into film cassetteand contacts the film as it loops down toward the mouth of the cassette.When the end of the film, which is attached to the cassette reel, isreached, the film in the cassette, between the reel and the mouth willbecome taut, deflecting finger 67. When finger 67 is deflected itcontacts a microswitch, not shown, which causes solenoid 64 to beenergized, moving rod 63 toward the right, as viewed in FIG. 1, androtating arm 60 counterclockwise until shaft 60 of pulley 59 bearsagainst rewind wheel 54. Shaft 60 will now frictionally drive the rewindwheel in the opposite direction that it drove the takeup reel. Since therewind wheel is connected to spindle 57 by shaft 55, the spindle and thecassette reel mounted thereon will also turn, rewinding the film ontothe cassette reel.

A film sensor 68, comprising a plastic reed which is unseated by film23, senses when the the film has cleared its station by seating, whichopens a microswitch in the operating circuit of solenoid 64 which isthen deenergized. Spring 65 then causes shaft 60 to disengage the rewindwheel and again engage takeup reel. The cassette is then removed fromthe projector, and the film is manually pulled out of the gate andshoved into the cassette until the end of the film is once againdisposed at the mouth of the cassette.

lclaim:

1. In a motion picture projector having a frame, a gate for receiving astrip of film having a series of frames developed therein and guiding itthrough the projector, said gate including an aperture for displayingframes, and a film-driving mechanism for driving a strip of film throughthe gate, a device for coding any desired frame on the film to initiatea desired operation upon display of the frame in the aperture comprisingpunching means to form a notch in the edge of a film strip, and sensingmeans to detect a notch in the edge of a film strip, said punching meansand said sensing means being located in the gate at the same point inthe path of the film.

2. The invention defined in claim 1 wherein the punching means comprisesa hollow cylinder having one side partially cut away, and overlappingthe film, and the sensing means comprises a pivoted arm having one endwhich extends into the hollow cylinder and is held against the edge ofthe film by a spring means, and having its other end in operableassociation with a switch, whereby the switch is operated upon pivotingof the arm.

takeup reel is empty and

1. In a motion picture projector having a frame, a gate for receiving astrip of film having a series of frames developed therein and guiding itthrough the projector, said gate including an aperture for displayingframes, and a film-driving mechanism for driving a strip of film throughthe gate, a device for coding any desired frame on the film to initiatea desired operation upon display of the frame in the aperture comprisingpunching means to form a notch in the edge of a film strip, and sensingmeans to detect a notch in the edge of a film strip, said punching meansand said sensing means being located in the gate at the same point inthe path of the film.
 2. The invention defined in claim 1 wherein thepunching means comprises a hollow cylinder having one side partially cutaway, and overlapping the film, and the sensing means comprises apivoted arm having one end which extends into the hollow cylinder and isheld against the edge of the film by a spring means, and having itsother end in operable association with a switch, whereby the switch isoperated upon pivoting of the arm.